Evening star. [volume] (Washington, D.C.) 1854-1972, 1887-12-06
CITY AND DISTRICT.
IMPROVEMENT OF ROCK CREEK,
Engineer &c mr,,issionerI .udlow,s plan
Submitted 10 Congress.

Engineer Comr,issioner Iudioys,s plan
submitted 10 Congress.
IU% PROPOSED TUNNEL AND HOW 1T WILL IMPROVE
THE SANITARY CONDITION or THE DIsrRIcr-THE
AREA AFFEcTED-EsTIsArED COST OF THE I'M
TEovENEST, AND OTHER POINTS.
Following Is the plan which has been prepared
b. Engineer Commissioner Ludlow for the i'm
prOVement OF Rock Greek, which was submitted to
congress to-day by the District Commissioners as
an appendix to their report upon the subject.
To N Hoard Of Commissioners Of the District Of
GENTLEMEN: The following project for the con-
struction OF an artificial conduit TO convey the
waters Of Rock Creek In tunnel between Lyons
mil and Pennsylvania avenue, as substitute Tor
the present creek bed between the points named.
has been prepared In compliance with the fol-
lowing resolution OF the board:
'NoyKxBER TO- 1887.
Resolved, That the Engineer Commissioner is
hereby requested 10 prepare for the consideration
o. this board In time for Transmission 10 Congress
with the annual report OF the Commissioners Tor
the FISCAL year ended June 30 1887, project, with
estimates OF cost and other data for a tunnel and
the most direct way practicable from Lyons mill
U the intersection OF said creek with Pennsyi-
yania avenue"
TOPOGRAPHY OF ROCK CREEK VALLEY.
The limited time as well the lack OF means
ble 10 secure the full and accurate data requisite
for final and satisfactory determination OF the
details OF the prODJeCt, and reliance has therefore
been had upon such general Information as was
accessible. Rock Greek traverseS the District
from It's northern angie In n direction about south
by west, following a tortuous and rocky channel,
which Is further ObStruCted by dams at several
points. The length OF the creek valley within the
District Is about miles, and the length OF the
miles. Northward from the District the drainage
area extends some - miles farther. and the creek
has IN additional length OF about l7k miles The
axis Of the drainage area therefore Is about 81
miles IA length and tie creek about 20 miles,
draining about ~ square miles Of territory. The
upper portion lying exterior the District the
State U! Maryland, Is mainly composed OF farm
lInds with moderate slopes, which tend to restrict
the velocity OF the Water in reaching the stream,
me District although the slopes are sleeper and at
times precipitOuS has a similar effect.
THE LOWER PORTION OF THE CREEK
constitutes the dividing line between the cities OF
Washington and Georgetown, and previous to the
construction OF the dam at the mouth In connec-
ton with the service OF the Chesapeake and Ohio
Canal, or which II constitutes the terminus the
tide OF the Potomac ebbed and flowed Tor a con-
siderable distance up the stream and the creek
poured Its free volume directly INTO the river.
The construction of the dam changed the charac-
ter Of the lower portion OF the creek converting
into a sack-vater level and harbOr for the canal,
and made IL a permanent recipient OF all waste
Elatters reaching the bed from the wash or the
slopes, deposits upon It's banks, or the more solid
contents OF the several sewers discharging into IT,
In cons quence OF this the bed has been partially
nlled with deposits OF this character, which the
low OF the stream, owing TO the absence OF scour
ing velocity at the bottom, Is unable TO remove,
and complaints have been made both OF the Often
sive Character OF the eXhalationS from the valley
and OF the unhealthfulness OF the vicinity, due TO
this and cOgnate causes
The creek is now spanned by three bridges, con-
Meeting Washington and Georgetown within the
limits designated VIZ, those on Pennsylvania
avenre at VI street, and street, none OF which Is
suited 20 It's work. whether In point OF dimensions
plan OF construction, or physical condition, and
frequent representation has been made OF the de-
STABILITY OF securing better ana more numerous
means OF transit for the growing population OF
both cities
IN TIE BETrERxENT OF THE SANITARY CONDITIONS
II would probably be necessary after removing the
dam ct the mouth OF the creek to condemn the
valley as park and thereafter keep It In order
at the public expense, this project involving the
further necessity OF constructing intercepttng
sewers 20 protect the water OF the creek from pol
luton. For improved communication it would be
add TO their numbers such others as should be
found advisable, but for the accomplishment OF
constpucrion a. an ari,c,ai condnt in re5,ace the
present creek bed as a preliminary 10 the subse-
Suent ooliteration of the valley by ning It up TO
the level OF the adjacent grounds 1t Is this propo
sitiOn upon which the board requests q project
anu estimates.
glance at the map readily discloses what
would be the site of a construction OF this kind.
The creek, after reaching Lyons Mill at point
near the junction OF 18th and streets, were
course TO street, east Of 2}d there bends sharply
TO the west ana north to the Intersection OF 25th
and ., and thence In a nearly direct southwest
cry course 10 the Potomac.
THE PROPOSED TUNNEL
tunnel from about Lyons Mill due south on
the line OF 18th street would cut OF the sharp
bend above referred TO, and the continuation OF
this construction in the open valley and bord-
eriny the stream would conduct the waters OF the
creek out Of sight between the terminal points and
make IL practicable to fl the valley to the level OF
Its upper margins The project thus outlined
rom an engineering point OF view, Is entirely
It's dimensions, and these In turn upon the volume
OF water 10 be provided for and the hydraulic
gradient adopted, In other words. the slope which
can be given 10 the water surface within the tun-
mel With regard TO the volume OF water in the
absence OF exact Information, certain data must
measurements and observations should precede
any actual constructions.
THE TOTAL DRAINAGE AREA
Is approximately Al square miles, over which no
full record OF rainfall exists from which an aver
age could be estimated, nor 10 It known that the
maximum or mean discharge OF the stream has at
any time been accurately ascertained From gen.
erel meteorological data &c Is safe TO assume That
the average maximum OF rainfall over the entire
area Will not exceed and one-naf inches In any
twenty-four houra This rate OF fall may be ex-
ceeded for limited periods and special localities as
for example that noted by Prof Henry In July
1865. when the rain gauge recorded fail Of 4 and
ninety-two hundredth inches In three and one
nan nOurS, Out sucn an abnormal Intensity may
be regarded as purely local and the general as
sumption for the entire area OF the Rock Creek
basin as wen within the limits OF safety and prob
adopt
A Ial OF ~ inches IN twenty -four hours over As
square miles would amount TO 470, As, 600 cubic
Feet OF AS cubic feet per second and this would
therefore represent the mean rate OF fall for a
storm OF maximum severity extending over the en-
Tire region and for the entire day. OF this amount
acerain proportion only could by possibi reach
the point Of discharge at any given time and this
proportion 10 Is needful TO estimate In order TO de-
termine what capacity the tunnel should have.
OBSERVATIONS OF the regimen OF Rock Greek tend 70
snow that not less than two days are required 10
discharge the food due TO a storm, but these OBJ
due 70 evaporation, absorption. and subterraneOus
nov, and IL will b. entirely sale to assume q low
estimate that three days will be needed to dis
charge the equivalent OF the total fall. This gives
ofle-third 81 5,445, SIS cubic feet per second
as the mean maximum now 10 provide for but as
the actual now az given time may exceed this,
II rfny De assumed, for the sake OF security as
ooutae this amount, or 3,6S0 cubic feet Four
thCisand cubic feet is therefore adopted as the
gratsst volume OF water that the tunnel will be
called upon 10 discharge.
THE NATTER OF GRADIENT
remains TO be determined The Hood marks on
the creek banks near Lyons Mill Indicate an eeva-
tiOn u about 1875 feet above city datum which is
mean hi n water in the Potomac With the slight
objection m the HE OF the tunnel this difference
In elevation Will give gradient OF .OO2gy2s and
CONDUIT Of pa square feet In area will discharge
4 AS cublL feet per second; or assuming that the
river surface Il . feet above mean high water, the